If what you said is right, then as long as he has 1 high skill (respectable) in the inside skills, and 1 high skill (respectable) in the guard skills, then they should all train faster right?
That would probably be too easy said also considering that respectable is not very high usually...
but yes, training skills in balance is faster than training a mono-skiller.
We have both said a lot of things that you are going to regret.